The invention relates to a screw-type compressor comprising a housing in which are arranged a primary rotor and a secondary rotor each having a shaft and a screw rotor.
Screw-type compressors are used for compressing a gaseous substance, e. g. air, and making it available as compressed gas. From DE-A-42 27 332 a screw-type compressor is known wherein a motor-driven primary rotor drives a secondary rotor. The shafts of the primary and secondary rotors are radially supported in roller bearings at both ends. Further, each shaft of the two rotors is axially supported in a plurality of ball bearings at one end. Said axial bearings carry the forces, which occur between the screw rotors during gas compression, in axial direction of the primary and the secondary rotor. The antifriction bearings produce heat during operation, which leads to inhomogeneous heat distribution and thus to stresses in the shaft. From DD-PS 84 891 and U.S. Pat. No. 3,811,805 compressors are known whose primary and secondary rotors are each provided with axial bearings which are configured as slide bearing and thus produce less heat. U.S. Pat. No. 3,275,226 describes a screw-type compressor wherein the primary and secondary rotors are axially supported by antifriction bearings with the primary rotor being additionally axially supported by a disk. The multitude of bearings for the primary and the secondary rotor render the configurations of the known screw-type compressors complicated and their manufacture expensive.